Hydraulic control valve



Jan. 8, 1946. w. T. STEPHENS HYDRAULIC CONTROL VALVE Filed Nov. 9, 1942 dwTwAooH Wmawwwmw MHOZErO Marin NT zwom .naom mdawwwm 5mn 25,6 wznwmmam WILLIAM T STEPHENS ,EM

laying tractors.

4novel and simply constructed hydraulic valve Patented Jan. 8, 1946 UNITED STATES l2,392,422 PATENT oFFlcE Y 2,392,422 HYDRAULIC CONTROL VALVE William T. Stephens, Cleveland, Ohio, asslgnor to Hydraulic Control Engineering Company, Cleveland, Ohio, a corporation of Ohio Application November 9, 1942, Serial No. 55,059

9 Claims.

'I'he present invention relates to a hydraulic system and control apparatus therefor and, more particularly, to a hydraulic control for tensioning steering bands, applying braking bands,

clutching and declutching prime movers. from 5 drive shafts, and arresting movement of planetary transmissions of tractor vehicles, especially track- The invention contemplates a clutch for coupling and uncoupling the track driving mechanism to the tractor power plant. 'I'he steering, braking and declutching of the driving mechanisms of both types have heretofore been operated by manually positioned levers.

Steering for the first type of 'tractor drive vwherein disk clutches are utilized is accomplished by disengaging the driver or sprocket clutch on the side toward whichthe vehicle is to be turned and simultaneously continuing the application of power on the opposite side. Thus, the vehicle pivots about the undriven or dead track. In

- braking, the driver clutches are first disengaged to protect the clutches from the destructive action which would result from the retarding action of the brakes while the clutches-are still transmitting power from the engine.

In steering and braking the second type of tractor using a, planetary transmission for driving the chain sprockets, la brake is appliedto one side driver to retard or stop its motion while allowing motion on the opposite driver, generally at an increased speed. Thus, the steering is quite similar to the first type.

braked. In practicing this invention the individual braking bands, steering bands, planetary transmissions, and clutch disengagers of track-carrying tractors are actuated by conventional hy.v

draulic cylinders, pistons or jacks receiving fluid from a closed hydraulic pressure system and do v'not form a part'of this invention per se. The operation of these devices andv their sequence of application is by means of a hydraulic valve and valve arrangement and forms the salient feature ot this invention, The broad concept of the in'- n -vention and the generic principles yoi vthe valve 60 closed in Fig. 2, to permit the ilowof fluid there- 40 clutch cylinder 5|.

per se are disclosed and claimed in my copending application, Serial No. 455,955,4led August 24, 1942, of which this application is a continuation in part.

In the drawing: Y Figure 1 is a .diagrammatic layout of the hydraulic cylinders for operating the brakes, steering bands and declutching cylinder of both types of track-laying tractors with the hydraulic con- 10 trol,valve therefor shown in cross section; and

Figure 2 is a fragmentary vertical section y through the valve plungers and portion of the valve casing'taken on line 2-2 in the direction of the arrows.

13 These several operations of steering-the tractor either to the right or left, the application of the brakes to stop the tractor, and the removal of power to the drive axles at substantially the moment the brakes are applied, may be readily 20. controlled by the use of a valve and hydraulic .system means having the novel features of this invention.

To enable those skilled in the ari'l to understand the broad aspects of operation of' this inggjventionl the following is a general description thereof.

With the present control valve in neutral or non-operative position, as shown in the drawing, oil from a suitable pump in the closed hy- 3 draulic system 'enters the valve casing through |3'extending through the casing, andv control the hydraulic fluid passing through the valve and leading to exterior piping connected to steering cylinders i5, I5', braking cylinders |1', and y It 'will be understood lthat -these hydraulically operated devices, diagrammatically shown, are provided with suitable pistons and linkages for connection to and operation of the .friction bands and brakes of the tractor steering and braking mechanisms and the When it is desired Ato stop the vehicle, both side drive shafts are clutch of the tractor engine. These conventional mechanisms per se form no part of the present invention.

The cylindrical reciprocal va1ve plugers ll- 50 and are identical in construction and each 55 carry threaded bushings 29 through which extend the stems 3| of the secondary. relief'valves 3l which normally engage apertured valve seats Il.

yThe body portions of these secondary relief valves are substantially square in cross section', as disare 35 mounted in, spaced parallel horizontal bores I3,

fluence of springs 4| positioned in the longitu dinal bores I9 of the valve plungers and pressing on the ends of the relief valve stems 3|.

The operation of either pair of steering and 4 braking cylinders I5, I1 and I5', I1', is identical and, thus, to project the actuating piston in steering cylinder I5, the valve plunger II is movedv partially inward to a position Where the high pressure fluid in the system will flow through inlet I and passage 3 to passage 1 and Ithence to passage 45, around groove 25 and, at the same time, close off communication between passage 3 and passage 5 bythe enlarged end of the outer stem portion of the plunger. The position of groove l25, following this initial movement of the plunger to where it bridges passages 1 and 45, allows oil under pressure'to flow Ithrough port 43 of the outlet plug and through the connecting conduit to cylinder I5 to thereby move the piston therein to operate and apply this steering band of the tractor. The pressure fluid also flows lto braking cylinder I 1, but, inasmuch as the braking cylinder is set so as' to lnot operate under 100 pounds per square inch, and the steering cylinder is set to operate at 50 pounds per square inch, only the steering cylinder and piston function at this pressure. i

The partial inward movement of the plunger II and compression of the spring of the associated relief valve 33 places a pressure of slightly above 50 pounds per square inch on'head 31 and, consequently, as soon as the steering cylinder I5 set for this pressure has functioned, the back pressure will raise head 31 from its seat and allow the fluid to bypass through opening 39, passage 49, around the square head of the relief valve to passage 41 coupled to a return linevleading to the reservoir of the system. The spring loading and compression thereof is such that the plunger I I will not move sufficiently for the land 2| to close off communication between passage to the clutch operating cylinder 5| through passage 49 and port 53 leading to the clutch cylinder. This declutching action is accomplished by blocking the flow of oil by land 2| between pas- Y sages 49 and 41 due to the forcing of the valve plungers II and II' to the limit of their inward stroke land the placing of a spring loading on the relief valves 33 of above 50 pounds per square inch and less than 100 pounds per square inch.

Inasmuch as the flow of fluid to passage 41 is blocked by the lands 2| of plungers II and II' the oil is forced to circulate through passage 49 and, thence, to port 53 and clutch cylinder 5|. The piston in clutch cylinder 5| is set to operate at approximately 50 pounds per square inch and,

' consequently, when the limit of its stroke is reached, the clutch will be disengaged and the internal resistance therein'will build up to 100 pounds per square inch and, thus, operate the 49 and passage 41 when a pressure of 50 pounds y per square inch is maintained at port 43. However, when the piston in steering cylinder I5 reaches the limit of its stroke, the internal resistance therein rises above pounds per square inch and the relief valve opens as before described.

When the plunger II is retracted after operation of the steering cylinder to its original position, the spring loading on the relief valve 33 isv relieved and fluid from the cylinder I5 freely returns to the storage reservoir by lifting the valve 33 from its seat and owing around the seat to passage 41 connected to the fluid storage tank. The second valve plunger II' is similarly operated to energize the opposite steering cylinder I5', the partial movement of the plunger Il' controlling the right-hand steering cylinder.

When it is desired to stop or positively apply both brakes and disengage the power clutch of the prime mover it is accomplished by forcing both valveplungers II and II' to their innermost positions and, thus, iluid pressure willV pass through passage 3 to passages 1, 45 and 45', and through outlet ports 43 to both steering cylinders I5 and I5', and braking cylinders I1 and I1'. The steering cylinders operate and the oil pressure therein builds up to approximately 100 pounds per square inch to raiserelief valves 33 and bypass oil to passage 49. Oil then passes brake cylinders I1 and I1' that are set for this increased pressure.

Based on this general description of the operaltion of the present improved hydraulic control valve, it will be appreciated that the valve maybe used in several specific combinations. For instance, when it is desired to control a tractor of the first type wherein disk clutches are used for applying power to the driving sprockets, the present control is capable of operating the hydraulic cylinders for steering, braking, and declutching the power shaft. A modification of the control of this first type is involved where only steering and braking control is provided. In the second type of track-laying tractor control Awhere a planetary transmission is used for driving the chain sprockets, the present system may provide a means of steering, braking, and master clutch control, or a modification of this second type where only steering and braking control is provided. These `two main control systems and their modifications will now be described in some detail.

To carry out the control of a tractor using disk clutches where steering, braking, and declutch-` plunger II in a sufficient amount to produce a valve setting of secondary relief valve 33 of slightly over 50 pounds per square inch. When this is done, the land to the right of recess 21 of plunger I I closes off bore I3' between passages 3 and 5 and, at the same time, the groove 25 of the plunger `bridges passages 1 and 45 to allow oil from passage 1 to be communicated therethrough via passage 3 and high pressure inlet port I. The oil ows to passage 45 via bore I3 around groove 25 and thence to cylinders I5 and I1 through outlet port 43. After the piston in cylinder I5 has reached the end of its stroke and the pressure therein builds up to a point exceeding the spring setting of valve 33 in bore I3, the valve head 31 is cracked or lifted and the oil by-passes back to the storage tank by one of two routes. Thus, cil may pass through passage 39 Vin valve seat 35 vthrough passage 49, through` bore I3', around valve head 31', and through passage 41, or the oil may pass through passage 39 in valve seat 35 through bore I3,. around valve head 3'1, and through passage 41. When the plunger II is retracted and is returned to the neutral position by means of spring 4I, the pressure setting of relief valve 33 is simultaneously released andpermits a return flow of oil from cylinder I5 and thence through port 43 and passage 39 where it lifts valve head 31 and returns to the tank, as previously deasoman scribed. -The steering cylinder I3' is operated in a. similar manner by plunger Il'.

In the event that either plunger I I or I I is not moved inwardly sufficiently to produce a 50 pound pressure or other desired pressure setting to operateeithercylinder I or I5', the relief valves 33 and 33' will open at the lower setting and allow the oil to pass back to the tank without producing movement of the piston in' the steering cylinder.

To operate the brake cylinder I1, it is necessary that the plunger II be pressed in sufficiently to produce a relief valve setting in excessv of 100 pounds per square inch on the valve I3. When this is done, oil will then flow to both cylinders I5 and I1 and, since cylinder I5 is set to operate at a lower pressure than cylinder I1, cylinder I5 will function ahead of cylinder I1 land disengage the driver clutch before sufficient pressure is built up to operate brake cylinder I1. This sequence of operation assures the release of the driver clutch prior to the application of the brake. After brake cylinder I 1 has functioned and the piston therein has reached the end of its stroke, fluid pressure is built up exceeding the setting of the relief valve 33 and, consequently, the valve head 31 is lifted from its seat and the oil will pass back to the tank, as previously described. However, if the plunger I I has been pushed in a sufiicient amount, so that land 2I has closed bore I3 between passages 49 and 41, the oil can return to the tank only through passages 39, 49, I3' and through 41 In a similar manner, brake cylinder 'I1' is caused to operate by pressing in plunger II', and

the operation of either brake cylinder I1 or I1',

vas described, makes possible the turning of the 3 sequence of operations ceases after the brakes have been applied and the resulting build up of pressure reacts on valves 33 and 33'. When these valves are open, the oil can only pass into passage 43 and as this has been blocked by the plug-in port 53,. the reaction pressure is carried back to the main relief valve 55 and thevcil is by-passed vlal passage 3 to the storage tank. This type of control is used where some form of manual operator is provided for disengaging the main clutch.

Referring now tothe second general form of drive wherein a planetary transmission is used.

`tioned all the way in and this produces an idenand I3' between passages 49 and 41 and the oil thereupon flows to'and acts on cylinders I5, I5', I1 and I1'. When the cylinders I5 and I 5 have reached the ends of their strokes and sufficient pressure is built up to lift the valve heads 31 and 31' of valves 33 and 33', the oil is forced to fiow to passage 49 through passages 39 and 39' in valve seats 35 and 35'. Since both bores I3 and I3' are closed off between passages 49 and 41, oil flows from passage 49 to cylinder 5I via port 53. Consequently, when cylinder 5I has operated and the oil pressure is again built up, it reacts on cylinders I1, I1' and when these open fully the oil acts against relief valve 55 lifting itfrom its seat and allowing the oil to ow back through passage 9 to the storage tank. The setting of relief valve 55 is such that it always exceeds the maximum setting of the secondary relief valves 33 and 33' and thus assures the proper sequence of operations depending upon the setting of the secondary tion.

steering and braking control is provided, the sys- 1 tem operates substantially as before described, with the exception that port 53 is plugged olf and cylinder 5I removed or-not-used. Thus the tical condition to the flrst form of. controlwith the plungers all the way in. The passage of oil is the same as previously described for this condition except that the cylinders II and I1' are eliminated.

With the modified control of a planetary transmission system, the operation is identical t0 that of the modif-led control of the rst type of tractor, except, of course, the cylinders I1 and I1 have been eliminated and an independent clutch control is necessary for disengaging the main clutch.

Thus, the four customary ways of operating a track-laying vehicle have been described in detail and it is apparent that, while the'use of the present hydraulic control valve and system embraces these four systems, it is in no way limited thereto.

'I'he hydraulic operation of the steering cylinders and disengagement of the engine clutch prevents any tendency of 'the tractor to spin around when the brakes are applied and posi-v tively prevents the application of the brakes when the clutch is engaged and torque is still on the drive sprockets and, thus, the brakes will only be called upon to arrest movement of the tractor.

As a further safety feature for the entire hydraulic system, a Vspring tensioned main reliefv complished its useful work before this exces-r sive pressure is built up and the relief valve 55 is unseated. f l

Other forms oi" hydraulically operated units using a plurality of cylinders operating ina def? inite sequence and utilizing different operating pressures, or where it is desired to serially cperate a plurality of hydraulic devices some'of which operate at lower pressure than others, are

broadly included' within the scope of this invenwhatfciannis 1. In a hydrauliccontrolvalve of the type described, in combination, a casing having an inlet for oil under` high pressure,'a pairof power ports. f

a pair of similar bores,.a passage connecting said inlet to both bores, separate ducts connecting each power port to one lof said bores, a reciprocable plunger in each of said bores and each having a land normally isolating the associated duct from its bore, a groove in each ofsaid plungers movable therewith to connectthe duct to said passage whereby oil under pressure may flow to a power port, a ported valve seat for and open to each duct,a chamber connecting the seat ports, a relief valve biased to close each seat port from the chamber, each relief valve being housed in a compartment extending between said .chamber and a discharge passage for oil under low pressure, and means controlled by the valve plungers to isolate said chamber from said discharge passage whereby pressure is built up in the chamber when a relief valve is forced open by pressure, and an auxiliary power port from said chamber. y

2. In a hydraulic control valve'of the type described, in combination, a casing having an inlet for oil under high pressure, a pairof power ports, a pair of similar bores, a passage connecting said inlet to both bores, separate ducts connecting each power port to one of said bores, a reciprocable plunger in each of said bores and each having a land normally isolating the associated duct from its bore, a groove in each of said plungers movable therewith to connect the duct to said passage whereby oil under pressure may flow to a power port, a ported valve seat for and open to each duct, a chamber connecting the seat ports, a. relief valve biased to close each port from the chamber, each relief valve being housed in an end of each of said bores extending between said chamber` and a discharge passage for oil under low pressure, said lands being movable into said ends to isolate them from the discharge passage whereby pressure is built up in the said chamber when one or both relief valves are forced' open by pressure in said ducts, and an auxiliary power v, port from said chamber.

3. The valve as set forth in claim 2 in which the lands may move to provide communication between the high pressure passage and the power port ducts while the bore ends are associated with the discharge passage. Y

4. The valve as set forth in claim 2 in which the biasing for the relief valves is effected by a spring interposed between each relief valve and its corresponding plunger whereby the pressure closing the relief valve increases as the plunger is moved to open communication between the high pressure passage and a duct.

5. A hydraulic valve for controlling the vow of liquid under pressure to a plurality of related 'liquid actuated motor devices including a casing having a pair of valve plungers therein, each of said plungers being adapted forv controllingv the flow of liquid under pressure to a motor port, a

, livery of liquid under pressure to both first mentioned motor ports and for closing the connection plurality of fluid responsive devices, comprising a' valve casing having a pair of spaced bores there-v 3 through, reciprocable valve plungers in said bores,

power ports in the said casing the flow of fluid to which is controlled by the position of said valve plungers, apertured relief valve seats communieating withsaid power ports, fluid passages in said casing controlled by movement of said valve plungers, an inlet for fluid under pressure con- `valves mounted in said bores adjacent'the ends of said plungers and controlling the passage of fluid through said apertured valve seats, said seats leading to a common fluid discharge passage in front of said relief valves and having a third power port, a second common passage arranged behind the relief valves and adapted for connection to waste. the relief valves affording space for liquid flow between said discharge and waste passages, and means to project the plungers into the bores between said'discharge and waste passages whereby they are separated.

7. A hydraulic control valve adapted to govern a plurality of hydraulically operated devices, comprising a casing having an inlet for liquid under pressure and a plurality of power ports, a pair of spaced parallel bores extending through said casing, reciprocable plungers in said bores, spring projected valve heads mounted beyond the ends of said plungers and positioned each to close an aperture in' a valve seat in the end of one of said bores, each said aperture being in communication with one of said power ports, a plurality of transverse fluid passages joining'said bores, one being connected to said inlet and one being connected to waste, lands on each reciprocable plunger for selectively controlling the ow of liquid under pressure to and from its power port, said lands being jointly in control of the said transverse passage connected to waste to isolate the bores and ports therefrom, said heads being in control of another of said transverse passages and a third power port connected to the last mentioned passage. v

8. A valve comprising a casing having an inlet and an outlet, bores through said casing, each bore having a valve plunger reciprocable therein, a forwardly projecting head on each plunger having an area less than the bore, a fluid passage communicating with each bore, controlled by. the plunger therein and leading to a motor'port in said casing, an apertured valve seat in the forward end of each bore and in open communication with the corresponding motor port, transverse fluid passages joining said bores on 'the plunger sides of said heads and one connected to said outlet and one to said inlet, means for applying the heads of said valve plungers against said seats at a varying pressure, means to close one of the transverse passages by said plungers to prevent flow thereto past said heads and a transverse passage connecting said bores on the seat side'of said head and having a separate motor port.

9. A valve as set forth in claimt? wherein the reciprocable valve plungers are hollow for the reception of springs, and the valve heads closing the apertured valve seats are progressively pressed into tighter engagement therewith by movement of said valve plungers.

WILLIAM T. STEPHENS. 

